Strapping machine



April 8, 1958 L. R. KALB 2,829,714

STRAPPING MACHINE Filed Nov. 8, 954 4 Shgets-Sheet 1 INVENTOR. BY I. fiKa/Lb April 8, 1958 L. KALB STRAPPING MACHINE 4 Sheets-Sheet 2 Filed Nov. 8, 1954 INVENTOR. .55 Jim L b p l 8 1958' Y 1.. KALB I 2,829,714

STRAPPING MACHINE Filed Nov. 8, 1954 5 4 sheets-sheet s I on IN VEN TOR.

April 8, 1958 L. R. KALB 2,829,714

. STRAPPING MACHINE Filed Nov. 8, 1954 4 Sheets-Sheet 4 30b 32b V I ll] i for packing purposes.

United States Patent STRAPPING MACHINE Lennart Reinhold Kalb, Akers Rune, Sweden Application November 8, 1%4, Serial No. 467,544

6 Claims. (CL 164-109) This invention relates to so-called strapping machines Machines of this kind are provided with stamping andpressing. tools adapted to stamp out or to partially stamp out hook-shaped tongues or similar interlocking elements in two over-lapping end portions of the strap or band, preferably made of steel orother metallicmaterial, said tongues being forced into interlocking engagement with each other so as to form a locking joint for the ends of the strap. The hooks or. tongues have such a shapeithat they engage each other in the locking position when the ends of the strap slide a. short distance along one another longitudinally of the strap in a direction tending to separate the strap ends from each other subsequently to the stamping and pressing operation.

A joint of this kind will be released it for one reason or another the strap ends slide back into their original position.

The main object of the present invention is to supplement the hook joint, in the same operation as stamping out or punching the said hooks, with particular counter hooks adapted toprevent the strap ends from sliding backwards and thus to prevent the joint from. beingreleased inadvertently. To this purpose, according to the invention, the stamping andpressing tools effecting said interlocking hooks in both ends of the strap are also adapted to make one. or more additional tongues or. counter hooks of such a shape that while permitting the ends of the strap to slide to. the interengaging position of the locking hooks they will snap over each other so as to form a catch or lock in said interengaging position for preventing theends of thestrap from returning in a direction tending to release the hook joint.

For making a hook joint with two or more locking hooks spaced from one another in the tie direction 1 preter to arrange the stamping and pressing tools in such a manner that in addition to said locking hooks they will also stamp out counter hooks at least in one of the spaces between said locking hooks.

One embodiment of the invention will now be described with reference to the accompanying drawings in which:

Figure 1 shows part of astrapping machine, partly in section andprovided with devices according to the invention,

Figure 2 is a section of the same machine. on the line IL-II in Fig. 1,

Figures 3 and 4 show perspective views of particular parts of the machine,

Figures 5, 6 and 7 are sectional views showing different operation stages during the manufacture of the joint, Figure7 illustratinga section of the joint on the line VII-VII in Figure 8, and

Figure 8 is a plan view of a finished joint.

Figure 9-is a plan view of a band having counter hooks only to'illustrate the counter hooks.

Figure 10 is a section through the device of Figure 9.

2,829,714 Patented Apr. 8, 1958 ICC Figure 11 is a section similar to Figure 10, but with the locking lugs in locking position.

Figure 12 is a section on a larger scale showing how the locking lugs, as seen in Figure 10, are formed.

In the several figures the same reference characters denote the same parts.

The machine illustrated in the drawings comprisesa base plate 1, a casing 2 and a side wall 6 which together form a. frame or support for the working parts of the machine. These parts are a stamping and pressingtool, a cutting tool and a strapping or stretching device. The main element of the first-mentioned tool consists of a stamp or punch 10 and a die 27 (seealso Figs. 3 and 4) and the driving mechanism of'the stamp. This mechanism comprises a wheel 8 journalled to rotate on a shaft 9 which is fitted in a recess 9ain the stamp 10, and a lever 3. mounted on a sleeve 5 which is attached between the casing 2 and the side wall 6 by means of a bolt 4 with a nut '7. An intermediary link 14, 15 is journalled on the shaft 9 and cooperates with a hook 13 on the segment 3a of the lever 3. At the stamp 10 tiere is secured an angular piece 12, 12a by means of a pin 11 fitted in a boring 11a. Segment 3a engages a peripheral groove 8a of wheel 8.

The stamp it) also has two teeth and 26, respectively, and the die 27 is provided with two teeth 28 and 29. Viewed perpendicularly to the longitudinal direction of the strapping band a, 3012 (Figs. 7 and 8) the teeth have an inclined contour similar to saw-teeth with certain edges being mainly parallel to the motion direct pingor tightening direction of the adjacent part o f the strap. The. teeth 25, 26 and 28, 29 are located and shaped in such a manner that at least two edges of the die 27 mainly parallel to the direction of motion of the stamp will. be situated opposite to or in registering position with each of two similar edges on the stamp 10 while an: inclined or oblique edge between said edges on the die is at least mainly parallel to an inclinedor oblique edge between the edges on the stamp.

The cutting tool consists-of a knife 20 on .the stamp ltlwand a counter cutter 21 resting on the: baseplate 1; The strapping or stretching device consists of a knurledor channelled plate 16 in the base plate 1, a

tension roller 17 and levers 18 and 19. By means of an oscillating movement of the lever 18 the tension roller 17 can .be rotated step-by-step in an anti-clockwise direction together with a shaft 13a by means of a ratchet wheelmechanism (not shown) adapted to eifect a feed ing movement in one direction only. The shaft 18a is journalled in an eccentric not shown which is mounted to rotatein the casing 2 by means of the lever 19 so that on swinging saidlever in one direction the tension roller 17 is caused to approach the knurled plate 16 while a swinging movement of the lever in the opposite direction will cause the opposite eflect.

In operation the machine is placed with the plate 1 resting on the load to be strapped. The outer free end of the strap (for instance a steel band, if desired coiled in the form of a roll) is introduced from the right in Figure 1 below the counter cutter 21 between the stamp 10 and the die 27 over the angular piece 12:; and between the knurled plate 16 and the tension roller 17. Then the strap is passed around the package and introduced on the strap part already inserted in the machine but this time the strap is laid between the knives 20 and 21. Subsequently the two strap. parts are compressed between the tension roller 17 and the knurled plate;-.16 by means of the lever 19 so that the lower part will be terial therebetween (see Figs. 12, 9 and 10).

3 firmly held against the channels of the knurled plate whereupon by means of an oscillating movement of the the knives will then be cut from the remaining part of i the strap roll.

Fig. illustrates the position immediately after this stage. The lower strap part is shown at 30a and the top strap part at 30b. The stamping or punching operation to make the locking hooks has just started. The surface die 27 in cooperation with the recess 24 in the bottom surface 23 of the stamp cuts the locking hooks or tongues 31a, 31b in the strap parts 30a, 30b and the free end of strap part 30b is bent down to strap part 30a by the action of the vaulted part 27a of die 27 in cooperation with a correspondingly shaped recess in stamp 10 adjacent knife 20. The teeth 25, 26 and 28, 29 have just been brought into contact with the strap parts so as to make the counter hooks 32a, 32b therein.

The counter hooks 32a, 32b are formed in the following manner: On depressing the stamp 10 towards the die 27 the edges of teeth 25, 26 of the stamp 10 in cooperation with the edges of the teeth 28, 29 of the die 27 will make cuts in the two straps 30a, 30b, said cuts having the shape of two spaced Us with the openings of the Us facing one another and with a bridge of uncut ma- Thus, the hooks or tongues 32a, 32b will not be entirely punched out from the material of the straps 30a, 3% but said hooks will remain a part of the straps at the uncut middle portions. At the same time the teeth 25, 26, 28, 29 act to turn the hooks 32a, 32b so that they will occupy an inclined position as shown in Fig. 6, Fig. 10 and Fig. 12. r

The locking operation of tongues or hooks 32a, 32b is shown more clearly in Fig. 11, from which it will be clear that on displacing straps 30a, 30b in opposite directions the tongue 32a will ride below strap 30a and tongue 32b will ride above strap 30b and the two tongues 32a, 32b will abut against each other along one edge so as to prevent the straps 30a, 30b from sliding back.

In Figure 6 the pressing and stamping operation is completed. From this position the lever 3 is returned to the right in Fig. 1, the stamp 10 being first raised from its engagement with the strap parts and subsequently the element 12a will catch the strap parts from below so as to raise and release them from the die 27. In conjunction therewith the pressure on the tension roller 17 is relieved by means of the lever 19 so that the strap parts will be permitted to slide along one another longitudinally in a separating direction, thus causing the locking hooks or tongues 31a and 31b to engage one another and to complete the joint as shown in Figs. 7 and 8. The counter hooks or tongues 32a and 32b produced during the stamping and pressing operation simultaneously with the locking hooks or tongues 31a, 31b can slide over each other from the position according to Fig. 6 while permitting the strap parts to spring apart to a certain extent but in the position according to Figs. 7 and 8 during the springing-back motion of the strap parts the counter hooks are caused to interengage one another and thus to prevent the strap parts from sliding back. The stamping and pressing tool for making the counter hooks is placed between the stamping and pressing tool for two adjacent locking hooks. Thus, in the finished joint the counter hooks will be placed in such portions of the strap which are maintained firmly pressed towards one another so that only by, an intentional and forceful external action they may be caused to spring apart to a zuffilgient degree so as to permit release of the counter What I claim is:

1. A strapping machine comprising stamping and punching means for punching locking tongues in two overlapping end parts of a strap, said tongues being shaped so as to interengage with one another to form a hook joint joining the end parts of said strap when said end parts of the straps have been caused to slide a short distance along one another longitudinally of the strap in a strap-end separating direction, said stamping and punching means also being adapted to punch counter tongues with such a shape that while permitting the ends of the strap to slide to the interengaging position of the locking tongues said counter tongues will snap over one another so as to prevent the ends of the strap from sliding backwards in a joint releasing direction.

2. A strapping machine according to claim 1 wherein the stamping and punching means is adapted to punch counter tongues at least in one space between two adjacent locking tongues.

3. A strapping machine according to claim 1, comprising a stamp and a die having teeth for punching the counter tongues, said teeth, viewed perpendicularly to the longitudinal direction of the strap, having an oblique contour similar to saw-teeth with some edges substantially parallel to the direction of motion of the stamp, and alternating with said first-mentioned edges, further edges arranged between the first-mentioned edges and inclined or oblique to the said direction of movement and exteding from the root of the tooth to the point of the tooth towards the tightening direction of the adjacent strap part, said teeth being located and shaped in such a manner that at least two edges of the die substantially parallel to the direction of movement of the stamp are situated opposite to or registering with each of two such edges on the stamp and wherein an oblique edge situated between said edges on the die is at least substantially parallel to an oblique edge between the edges on the stamp.

4. A strapping machine comprising punching and stamping means for forming locking tongues in overlapping strap ends, said tongues being so constructed and arranged that they interlock only upon tension in the strap causing slight motion of said strap ends, said punching and stamping means also forming latching means that upon occurrence of the slight motion required to cause interlocking of said tongues become operative to prevent movement of the strap ends to release said locking tongues when said strap is placed under compression.

5. A strapping machine comprising stamping and punching means for punching locking tongues in two overlapping end parts of a strap, said tongues being shaped so as to interengage with one another to form a hook joint joining the end parts of said strap when said end parts of the straps have been caused to slide a short distance along one another longitudinally of the strap in a strap end separating direction, said stamping and punching means also being provided with portions adapted to form a pair of spaced parallel incisions lying generally crosswise of said straps through both overlapping strap ends and to twist the portion of the straps lying between said incisions in a direction opposite to the direction of punching said locking tongues.

6. The strapping machine of claim 5, in which the distance between said parallel incision is only slightly less than the distance of sliding required to interengage said hook joint.

References Cited in the file of this patent UNITED STATES PATENTS 184,397 Macurnber Nov. 14, 1876 FOREIGN PATENTS 603,802 Germany Oct. 10, 1934 802,327 France June 6, 1936 

